Banca de DEFESA: PAMELLA PRYSCILA DE ALVARENGA BISSOLI MACIEL DE LIMA

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
STUDENT : PAMELLA PRYSCILA DE ALVARENGA BISSOLI MACIEL DE LIMA
DATE: 03/03/2022
TIME: 14:00
LOCAL: https://us02web.zoom.us/j/7575718156?pwd=SVZ3K2xxNC9DQXlZYm9OL3U1cXBJUT09
TITLE:

Influence of photolyase in the UV irradiation tolerance of Metarhizium and the impact on biological control of Rhipicephalus microplus.

KEY WORDS:

Entomopathogenic fungus, sunlight, visible light, UV-B, CPD photolyase

PAGES: 32
BIG AREA: Ciências Agrárias
AREA: Medicina Veterinária
SUBÁREA: Medicina Veterinária Preventiva
SPECIALTY: Doenças Parasitárias de Animais
SUMMARY:

The control of Rhipicephalus microplus has been carried out using chemical acaricides, but their indiscriminate use contributes to the emergence of resistant tick populations, accumulation of these substances in animal products and contamination of the environment by dumping waste into the soil. Alternatives are sought that do not cause so much damage. The use of entomopathogenic fungi as biological control is an excellent alternative. Metarhizium is an entomopathogenic fungus and has been widely studied in the biological control of arthropods. Fungi are subject to abiotic factors, among which are relative humidity, temperature, and solar irradiation. The exposure of fungi to ultraviolet B (UV-B) radiation can cause genetic mutation and change in the physiological system, which may result in decreased virulence and delay in germination, in addition to causing the death of the fungal propagule. On the other hand, moderate exposure to visible light irradiation stimulates the production of conidia, synthesis of photoprotectors, pigments and secondary metabolites. Photoreaction enzymes, as photolyases, can increase the tolerance of these fungi to UV-B rays and perform DNA repair. The present study evaluated the tolerance of conidia and blastospores of the same Metarhizium spp. isolate to UV under laboratory and field conditions, analyzed the pattern of photolyase expression in blastospores 8h, 12h, 24h, 36h, and 48h after in vitro UV-B exposure, and studied the impact of UV-B irradiation on the virulence of conidia and blastospores for females of R. microplus. In vitro, conidia exposed to 4 kJ m-², 6 kJ m-² and 7 kJ m-² exhibited similar mean relative germinations 24 hours after exposure (23.5±2.3%; 16.11±0.4 % and 31.16±2.2% respectively). Blastospores exposed to 4 kJ m-², 6 kJ m-² and 7 kJ m-² exhibited relative germination of 83±2.5% and 91.4±0.8%; 20.7±1.6% and 51.3±1.5% and 4.5±0.4% and 15.5±0.4% 24h and 48h after UV-B exposure. In the environment, the relative germination of both propagules (conidia and blastospores) analyzed after 18h (conidia 90.2±1.3%; blastospores 95.7±0.3%) or 28h (conidia 93.3±1.3% %; blastospores 97.3±0.8%) showed no significant difference (P > 0.05). The peak of CPD photolyase gene expression in blastospores was observed 36h after the UV-B exposure. In the bioassay, avegares of females’ nutritional index, egg production index, and hatching percentage of untreated femaleswere statistically different from the indices of females treated with the fungus and not exposed to the irradiation. The analysis of how UV-B interferes with the tolerance and pathogenicity of the fungus is crucial for the fungus’ use in biological control in the field. The present study showed that conidia and blastospores of the same fungal isolate have different behavior in relation to exposure to UV-B in vitro, but under natural conditions, the propagules show a better recovery from the damage caused by UV irradiation. The expression of photolyase in blastospores exposed to UV was reported for the first time and demonstrated that this enzyme’s action follows the recovery in the germination of these propagules.

BANKING MEMBERS:
Presidente - 2221855 - PATRICIA SILVA GOLO
Interna - 2860277 - ISABELE DA COSTA ANGELO
Externo à Instituição - RONALDO ALVES PEREIRA JUNIOR
Externo à Instituição - CAIO MÁRCIO DE OLIVEIRA MONTEIRO - UFG
Externo à Instituição - WENDELL MARCELO DE SOUZA PERINOTTO - UFRB